Pressure-responsive device



Dec. 15, 1942. R. R. DONALDSON 2,304,732

PRESSURE RESPONSIYE DEVICE Filed June 10, 1940 ATTORNEY.

PBESSURE-RESPONSIVE DEVICE Robert B. Donaldson, Pittsburgh, Pa, assignorto John lVL Hopwood, Mount Lebanon, Pa.

Application June 10, 1940. Serial No. 339,691

30mins;

This invention relates to pressure-actuated devices and moreparticularly to pressure-actuated relay devices oi the type adapted torespond to a primary pressure or impulse and to send out a sendingpressure or impulse that is proportional to the primary pressure and atthe same time maintain the sending pressure constant at the particularvalue called for by the primary presdevice embodying a form of theinvention;

Figure 2 is an end .view 01' the device as seen in looking in thedirection of arrows 11-11 on P18. 1; and

Figure 3 is a view in transverse section taken on line HIHI of Fig. l. I

Throughout the drawing and the specification like reference charactersindicate like parts.

The device embodying the invention in the form illustrated in Fig. 1,comprises a hollow body i, the interior oi which is subdivided intochambers A and B by means of spaced flexible pressure-sensitivediaphragms 2 and 3. Chamber A is disposed to receive a primary oractuating impulse irom a pipe 4, and chamber B is arranged to receive asending pressure impulse from a supply pipe I which is transmitted fromchamber B to a sending line I to be utilized for operating a device (notshown) which may be located at either a remote or relatively shortdistance from the device. The supp y pressure received by chamber B fromsupply line I is maintained substantially constant by any suitablemechanism (not shown). The value of the pressure in chamber B isestablished and maintained by means of a valve mechanism 1 that isoperated by movement oi. diaphragms 2 and 3 and is, of course,determined and dependent upon the degree oi force exerted againstdiaphragms 2 and 3 within chamber A whether eflected by means 01 Thevalve mechanism is so constructed that air or other suitable pressuremedium is admitted from pipe 5 to chamberB to increase the pressuretherein in response to movement of diaphragms 2 and 3 in onedirection, 1. e., to the right as seen in Fig. 1, and to shut oi! theadmission of such medium and exhaust, the same from chamber B through anexhaust passage to reduce the pressure therein in response to movementof the diaphragm in the opposite direction.

Diaphragms 2 and 3 are urged in one direction by means of an adjustablecompression spring 8 located in chamber A and a compression spring Ilocated in chamber B. Spring 8 may be adjusted less than the pressurereceived by chamber A from pipe 4.

Body i comprises a bonnet or housing II which is closed at one end andopen at the other with the open end terminating in'an annular flange ll,an annular spacer ring it, and a bonnet or housing l3 in which chamber Bis formed. Bonnet It likewise is closed at one end and open at theother, the open and terminating in a iiange l4. Flange ii,spacer I2, andflange ll asshown in Fig. 1 have substantially the same diameter so thatthey may be placed one on the other in abutting relationship and boltedtogether by means of bolts or cap screws ll.

Diaphragms 2 and 3 are mounted in spaced relationship as an assembly orunit. This assembly comprises a tubular-threaded member I, having at oneend a head II. The outer face of this head is machined to form a flangeII to receive one end oi spring 9. The under side of head I! is machinedto provide a shoulder ll that extends through an aperture in diaphragm 3and serves to position the diaphragm. Diaphragm 3 is clamped tightlyagainst flange I. by means of annular ring 20 which passes over ll. Theinner face of member 2| is provided with a groove ii that terminates inan opening 22 leading into the space 23 between diaphragms 2 and 3 andthis space communicates with the atmosphere through a passageway 24 thatis drilled in spacing ring I2.

Passageway 24 and space 23 have communication with the interior ofchamber B through a port 25 drilled transversely through memberapressure medium orapurely mechanical means. 55 I6 and a longitudinalpasage 26 in member It and a valve port 21 formed in head l8. Valve port21 is controlled by valve 1 as will be described later on in connectionwith the description of the valve assembly.

The central portion of diaphragm 2 rests against spacer 28 which isprovided with-a shoulder 28 located in the central aperture of thediaphragm. The inner portion of diaphragm 2 is clamped tightly againstspacer 28 with a cap nut 28 threaded on the end of member l8.

The outer edge of diaphragm 2v is clamped between flange II which isrecessed at 8| to receive the diaphragm, and spacer l2, and the outeredge of diaphragm I is clamped tightly between spacer i2 and flange l4.Spacer I2 is recessed as 'at 8| to receive the outer edge of diaphragm3.

The means provided for adjusting the tension of spring 8 comprises atraveling nut 82 which has screw thread engagement with a rotatable butstationary screw 33 disposed within bonnet 18. The traveling nut isprovided with a shank 34 that extends into spring 8 so that the end ofthe spring in contact with the nut will be maintained in a fixedposition with reference to the axis of screw 33. In order to preventtuming of the nut as it is advanced or retracted along the screw, adowel pin II is provided. One end of pin 38 extends into an edge of thetravelinl nut while its outer end is disposed to slide in a guide-way orgroove 38 formed on the interior of bonnet It. The dowel pin andguide-way hold nut 32 so that it cannot rotate on screw 28. The screw isformed with a shaft 61 that extends through the closed end of bonnet l0and is provided at its outer end with a handwheel 38 whereby thetraveling nut may be moved along the screw to adjust the tension ofsprin 8 as required. A collar or flange 88 is formed on the shaft andthis flange is iournaled in a recessed bearing and packing gland. 40,packing 4| being interposed between flange 38 and the bottom of therecessed bearing and gland 40 to prevent the escape of air or pressuremedium along shaft to the atmosphere.

Valve 1 comprises a valve body 42 which is threaded through a threadedopening in the closed end of bonnet It. This valve body is hollow and isprovided with a valve seat 43 at its outer end through which pressurefrom pipe 6 is admitted into chamber B. Valve 1 also includes a valverod 44 which is disposed within the valve body and formed at its outerend with a valve element 45 which is mounted on a reduced end portion 46of the rod. The valve rod is urged in a direction to seat valve element45 on seat 43 by means of a relatively light compression spring 41. Oneend of spring 41 bears against the inner end opposite forces on thediaphragm assembly and a pressure medium is introduced into chamber Afrom pipe 4 then the valve-assembly will move towards the right as seenin Fig. 1, whereby valve element is lifted off its valve seat, and allowpressure from pipe 5 to flow into chamber B and into sending pipe 6. Assoon as the pressure in chamber B exerts a force on diaphragm 3 equal tothe force exerted on diaphragm 2 by the pressure in chamber A, valveelement 48 will be moved "1 to the left until it seats on valve 48 andshuts of! further introduction of pressure from pipe 8 into chamber B.At this point an equilibrium is reached and the device is in balance.

As has already been stated, if springs 8 and 8 exert equal and oppositeforces on the diaphragm assembly, then, as the pressure in pipe 4 andchamber A increases or decreases, the valve mechanism will be actuatedto establish a pressure in chamber B that is equal to the pressure inchamber A. If the pressure in chamber A remains steady but the pressurein line 5 varies because of leakage in line 8 or in the device (notshown) being operated by the pressure in pipe 4,the diaphragms 2 and 3will flex in such a direction that pressure frompipe 5 will beintroduced into chamber B to build up the pressure therein to therequired value. If the pressure tends to fall in chamber A, thediaphragms will flex in a direction to close the inlet to chamber B andopen the exhaust port 21, allowing pressure in chamber B to escapethrough the exhaust passages to the atmosphere. Therefore the pressuresin chamber B and in pipe 8 will always be equal to the value of pressuretransmitted to chamber A by pipe 4, and under steady pressure conditionsin chamber A the diaphragms and of valve body 42 and the other end issupported on a flanged collar 48 disposed over the middle portion of thevalve rod and resting on a shoulder 50 formed on the valve rod. Theinner end portion 5| of the valve rod extends into port 21 of head 11and serves to open or close the port. Port 21 is preferably conical inform so that it will keep valve rod 44 in line and make positive seatingof portion 81 in the valve port when it is positioned to close the port.

When the tension of spring 8 is adjusted so that it exerts a force equaland opposite to that exerted by spring 8, valve element 45 will beseated on valve seat 43 and the inner end of the valve rod will beseated to close port 21, whereby pressure may neither be exhausted fromchamber B nor introduced into it from the supply pipe 5.

Whenever the springs 8 and 8 exert equal and valve 1 will operate toregulate the pressurein chamber B and pipe I to a constant steady value.

If the compression of spring 8 is increased by turning the handwheel 38in a direction to move traveling nut 32 towards cap nut 28, the excessof force exerted by spring 8 in opposition to that exerted by spring 9will represent the equivalent of a loading pressure in chamber A. Thiswill mean that even though no pressure is transmitted from pipe 4 tochamber-A, the inlet port to value when the force of pressure exerted ondiaphragm 3 balances the force exerted by spring 8 over and above thatexerted in opposition thereto by spring 9.

With an adjustment such as above described, it follows that as thepressure in chamber A is increased the pressure in chamber B willlikewise be increased, but the pressure in chamber B will exceed that inichamber A by the amount of the loading imposed on the diaphragmassembly by spring 8. If the pressure in chamber A decreases thendiaphragms 2 and 3 will flex to the left as seen in Fig. 1 and uncoverthe exhaust valve port 21, allowing pressure to escape to the atmosphereuntil the pressure in chamber B has been reduced to a value that willbalance the force of the 'pressure in chamber A and the loading ofspring 8.

The device shown may also be used as a manually-operated sending device.Thus, if no pressure is transmitted to chamber A from pipe 4,

ece ved pressures may be sent out throu h p pe t bi? il'- justine thecompression of spring 0. through adjustment of spring t, it is possibleto have send ing pressure sent out through pipe 3 that will vary fromzero gauge pressure to tho mommum of the pressure in pipe 6.

No matter what loading is imposed by spring b when the device ismnnually operated, dia= phmgm 3 will act to regulate the pressure inchamber B and maintain it at e, value called for by the olndinz'oispring 8. v-While only a single form of my improved preosure-sensitiverelay device has been shown and described-and while only o single formof the improved valve mechanism has been disclosed, itwilibeapporenttothoseekiliedintheertthct various modifications andchanges may be mdc without either from the miter from the scope of he;invention Thereiore, what i cluim and desire to secure by Letters Patentis:

i. A relay for sending and maintaining presa hollow member locatedbetween them nt their middle portions, o clamping member extendingthrough said spacer and diaphremo and rigidly secured thereto butmovnble thercwit said spacer hcvinu o posceeeway opening into the spacebetween the diflDWi ii acid body having an exhaust cpeninc providing H11 mm; cation between the space between the diophrogms end theatmosphere, said clumping membm' mt ing a, passageway formed thereinextending from the chamber side thereof to the suid hollow mem ber,thereby providing at 's i rowdy from the interior of said chamber to theatmosphere, a valve body mounted on said relay body and hav ing an inletport adapted for connection to as source of pressure medium, a valvestem within said valve body and bovine e valve element adopted to seaton said inlet port, the other end of said valve stem extending into saidclimber and seating in the chamber end oi the way in said clampingmember, whereby in response to on actuating force being applied to colddiophregms in one direction, the valve stem is cure in the member on theoienhrcema are in ectuotcd to odmit hnnouro to void chommre, said inletend cold 9mm in when the force exertedbythepmsiueonaaid diaphragm '11:;the octuetins force and the inlet being closed and the exhaust isuncovered when the force of pressure excwdc the actuating force.

2.Arele.yioreendincpreesurectoaeendine line and such pwrea at valuesthat are proportional plied to tln relay, comprising a housing, a diephraem assembly forming a cloned chamber at one side thereof in soldhousing, actuating means on the other side of said diaphragm assemblyyieldingly urging the diaphragm assembly in one direction, vulvc moonsassociated withand actudied by said diophrcgm assembly fordeliveringpressure medium to the chamber and tending line until the premuretherein is of a value suiucicnt to the actuating force, said die.-phragm assembly comprising spaced dlaphragms, means for holding saiddiaphragms in spaced relotion at the edges and the middle portionsthereof, the holding means at the middle portioncoi the diaphragm beingprovided with a passage way establishing communication between thechamber and the atmosphere, there being on er heust valve sent formed atthe chomber end of sold passageway, the valve assembly having a valvestem one end of which is positioned to cover or uncover the exhaustvalve sent, the other end of the vulve stem controlling the inlet ofsaid balance, end to open the exhaust passase valve sent and close theinlet of the valve when the force exerted by the pressure on thediaphramns exceeds the opposing octuotine force.

3. A device according to claim 2 characterized by the fact that thevalve means comprises a body adjustebly mounted on the housing andextending into the pressure chemben'a valve stem extending throughmid'body and provided with e "valve element at one end odcpted to openor close the inlet port of the vulve body and havihc its opposite endudeptcd to be rwcived in the on haust volve cent associated with thediaphragm assembly, and means yicldineiy urging the valve stem in a.direction to close the inlet port.

nonm'r R. DONALDSON.

to an actuating force sp

